-LRB- CNN -RRB- -- Speaking Saturday at the Summit of the Americas , President Barack Obama said it is reasonable to debate alternatives in the war on drugs , but insisted legalizing drugs was n't a valid option in the United States .

Obama voiced his view in his first public remarks at the hemispheric event during a meeting of business leaders , where he was part of a panel alongside Brazilian President Dilma Rousseff and Colombian President Juan Manuel Santos .

The possibility of drug legalization has gained traction in Central America , which is being squeezed between suppliers to the south and consumers to the north .

Yet the idea goes against decades of the prohibitionist policy backed by the United States , which is largely followed and enforced in Latin America and the Caribbean .

Santos noted Saturday that people in his native Colombia , too , have called for different ways to approach illicit drugs .

`` Sometimes we pedal and pedal and pedal , and we feel like we are on a stationary bike , '' he said of the war on drugs . `` I think the time has come to simply analyze if what we are doing is the best we could be doing , or if we can find an alternative that would be more effective and less costly to society . This is a topic of extreme political sensitivity . ''

He added , `` One extreme can be to put all users in prison . On the other extreme , legalization . In the middle there may be more practical policies , such as decriminalizing consumption but putting all the efforts into interdiction . ''

The first thing that regional leaders should do , Santos said later at the summit 's opening session , is seriously and collaboratively examine how to tackle drug trafficking `` without dogma , without prejudice . ''

`` This summit is not going to resolve this issue , '' he said . `` But it can be a starting point to begin a discussion that we have been postponing for far too long . ''

Obama earlier Saturday left the door open for debate , but made it clear that the United States has a firm stance .

`` I think it is entirely legitimate to have a conversation about whether the laws in place are doing more harm than good in certain places , '' Obama said . `` I personally , and my administration 's position is , that legalization is not the answer . ''

Much attention in the run-up to the summit was on the drug issue , as well as on leaders from the hemisphere who are not present in the coastal city of Cartagena , Colombia .

Venezuela 's foreign minister told reporters Saturday that Venezuelan President Hugo Chavez will not attend because of health reasons . Chavez had recently returned to his country from Cuba , where he underwent cancer treatment .

Cuba , which is not a member of the Organization of American States , was not invited to join the leaders . But there was a last-minute push by Ecuador 's leftist President Rafael Correa to get Cuban leader Raul Castro a seat at the table .

Correa boycotted the summit because of Cuba 's exclusion .

Santos , a key U.S. ally , said in his opening remarks Saturday that it was time to overcome such issues -- calling it unthinkable if Cuba is not part of the next Summit of the Americas , as well as nearby Haiti .

The United States has `` never been more excited '' to work as equal partners with countries in Latin America , Obama said earlier Saturday -- a vow that 's been made before by U.S. presidents , but that nonetheless drew applause from the audience of business leaders .

The president presented an upbeat assessment of hemispheric relations , touting a 46 % increase in trade between the United States and Latin American and Caribbean countries .

`` This hemisphere is very well positioned in the global economy , '' he said .

Rousseff spoke of a need for a `` virtuous relationship '' based on respect and equality among economies , while Santos said he welcomed a `` change of mentality in relations between north and south . ''

Obama pointed out one change he 'd like to see : `` I think in Latin America , part of the change in mentality , is also not always looking at the United States as the reason for everything ... that goes wrong . ''

There are many examples of increased cooperation between the United States and Latin America , but they are not always flashy and do n't draw the same type of attention that conflicts do , Obama said .

`` Oftentimes in the press , the attention at summits like this ends up focusing on the controversies , '' the president added . `` Sometimes those controversies date back to before I was born . ''

The summit 's start was momentarily overshadowed by two security incidents -- one involving bomb blasts and another involving Secret Service in Colombia to protect the U.S. delegation .

Roughly a dozen Secret Service agents and officers are being investigated over early findings that they allegedly brought back several prostitutes to a hotel in Cartagena , two U.S. government sources familiar the investigation told CNN .

The Secret Service personnel have since been sent back to the United States .

Separately , two small blasts occurred nearly back-to-back Friday in Cartagena .

The explosions -- one near a bus station and another near a shopping mall -- occurred a good distance away from where world leaders were gathering , said Alberto Cantihho Toncell , a spokesman for the Colombia National Police .

There were no casualties , and only minor damage was reported , Toncell said .

The explosions came on the heels of a similar one earlier in the day near the U.S. Embassy in the capital city of Bogota , authorities said .

CNN 's Dan Lothian contributed to this report .

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NEW : Colombia 's president says it is unthinkable if Cuba is n't at the next summit

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NEW : Santos adds the summit can be a `` starting point '' for talks on illicit drugs

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Obama says debate is fine , but insists legalization is n't an option in the U.S.

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The United States wants strong relations with Latin America , Obama says